The Touch Bar is essentially a USB 2180x80 display, mounted for optimal viewing at a 45 degree angle.

So, it's a second monitor, a tiny, little, short, second monitor, in wide-color and the resolution of the MacBook. That's how Final Cut Pro X can display a live timeline, with sliders, on the Touch Bar.
Apple's trying to guide developers on what they should use the Touch Bar for, but virtual function keys are still encouraged.

For years, I've used macro programs to make my Function Keys useful. I print a clear plastic strip and tape it to my keyboard above the function keys so I can remember what's programmed. If Apple introduces a new keyboard with the Touch Strip, even if it has to be wired, I'll buy it.